#include <iostream>
#include <cmath>
#include <iomanip>
using namespace std;
double average(int a[],int len)
{
    double ave = 0.0;
    for(int i = 0; i<len; i++)
        ave = ave + a[i];
    return ave/len;
}
int main()
{
    int N;
    cin >> N;
    int * a = new int[N];
    for(int i = 0; i<N; i++)
        cin >> a[i];
    double sum = 0.0;
    double ave = average(a,N);
    for(int i = 0; i<N; i++)
       sum = sum + pow((a[i] - ave), 2); 
    cout<<fixed<<setprecision(5)<<sqrt(sum/N);
    delete [] a;
}